Choice-supportive bias

When you choose something, say a boyfriend or girlfriend, you tend to feel positive about it, even if the choice has flaws. For example, you may think your dog is awesome — even if it bites people every once in a while — and that other dogs are stupid, since they're not yours.

Inter-group bias

AP

We view people in our group more favorably than someone in another group. This bias helps illuminate the origins of prejudice and discrimination. Unfortunately, researchers say we aren't always aware of our preference for people in our social group.

Reactance

One study found that when people saw a sign that read, "Do not write on these walls under any circumstances," they were more likely to deface the walls than when they saw a sign that read, "Please don't write on these walls." The study authors say that's partly because the first sign posed a greater perceived threat to people's freedom.

Reciprocity

We learn the reciprocity norm from a young age, and it affects all kinds of interactions. One study found that, when restaurant waiters gave customers extra mints, the customers upped their tips. That's likely because the customers felt obligated to return the favor.

Salience

For example, research suggests that we often treat "token" minority members of a group as stand-ins for the group as a whole. So if there's one woman on a business team and she performs poorly, we may assume that women in general are poor performers.

Stereotyping

There may be some value to stereotyping because it allows us to quickly identify strangers as friends or enemies. But people tend to overuse it — for example, thinking low-income individuals aren't as competent as higher-income people.